Vancouver Aquarium killer whale experts have teamed up with American researchers to monitor and record images of Northern Resident killer whales using a drone.

Hovering 30 metres above pods of orcas, the drone's camera allowed scientists to see the whales from a much different perspective than from a nearby vessel. Some whales were clearly pregnant, a condition not always visible by boat.

"This will help us understand how often they lose calves in the first few months of life. It's something we've always wanted to know. We know a lot about the calving rate, but we don't know how often stillborn or neonate or early childhood births occur," said Dr. Lance Barrett-Lennard, the Aquarium's senior marine mammal scientist.

Barrett-Lennard teamed up with U.S. researchers Dr. John Durban and Dr. Holly Fearnbach from the National Oceanic and Atmospheric Administration (NOAA) in San Diego.

Other whales were quite thin, their reduced girth evident from the air. Scientists could easily detect a condition known as "peanut head," where the white eye patches taper inward on underweight animals. One female, named I-63, was so thin she disappeared from the pod a week later and is presumed dead.

More than 60 flights were carried out over Johnstone Strait in August.

The APH-22 marine hexacopter captured the images of 77 Northern Resident killer whales and five transient killer whales.

Barrett-Lennard said most of the whales appeared to be in good condition as there was an ample supply of chinook salmon in the area to feed on.

Scientists plan to keep using the drone since it doesn't have any impact on the whales and the information it provided was so valuable.